Pre-entry screening programmes for tuberculosis in migrants to low-incidence countries: a systematic review and meta-analysis

Interferon-gamma release assays can effectively screen migrants for the tuberculosis infection, but urgent, active cases need clinical recognition

AIM

Increasing numbers of migrants to Sweden are screened for tuberculosis (TB), and a rational approach to screening is required. We evaluated positive tuberculin skin tests (TSTs) and interferon-gamma release assays (IGRAs) on paediatric migrants in relation to the TB incidence in the corresponding foreign-born populations in Stockholm.

METHODS

This study examined the characteristics of migrants under the age of 18 who were referred to a paediatric TB clinic at Karolinska University Hospital from 2008 to 2014 by primary care centres in Stockholm County.

RESULTS

We saw 943 TST-positive children with a median age of 14 years at the TB clinic and performed IGRAs on 557. IGRA positivity ranged from 64% in migrants from Somalia to 20% in those from the former Soviet Union and eastern Europe, with an estimated population level prevalence of 18.8% and 4.2%, respectively. These were significantly correlated to TB incidence in foreign-born Stockholm children. We diagnosed active TB in 20 screened migrants, and advanced, symptomatic TB was diagnosed in 10 recently arrived migrants without screening.

CONCLUSION

IGRAs showed higher specificity than TST in identifying tuberculosis. TB screening should focus on migrants from high-incidence countries, but this may be inadequate to detect advanced TB cases.

Lessons learnt from TB screening in closed immigration centres in Italy

Background

Between June 2012 and December 2013 Médecins Sans Frontières launched a pilot project with the aim of testing a strategy for improving timely diagnosis of active pulmonary TB among migrants hosted in four centres of identification and expulsion (CIE) in Italy.

Methods

This is a descriptive study. For active TB case finding we used an active symptom screening approach among migrants at admission in four CIE's. Here we describe the feasibility and the yield of this programme.

Results

Overall, 3588 migrants were screened, among whom 87 (2.4%) had a positive questionnaire. Out of 30 migrants referred for further investigations, three were diagnosed as having TB, or 0.1% out of 3588 individuals that underwent screening. Twenty-five (29%, 25/87) migrants with positive questionnaires were not referred for further investigation, following the doctors' decision; however, for 32 (37%, 32/87) migrants the diagnostic work-out was not completed. In multivariate analyses, being over 35 years (OR 1.7; 95% CI 1.1–2.6) and being transgender (OR 4.9; 95% CI 2.1–11.7), was associated with a positive questionnaire.

Conclusions

TB screening with symptom screening questionnaires of migrants at admission in closed centres is feasible. However, to improve the yield, follow-up of patients with symptoms or signs suggestive for TB needs to be improved.

Improving Control of Tuberculosis in Low-Burden Countries: Insights from Mathematical Modeling

Tuberculosis control and elimination remains a challenge for public health even in low-burden countries. New technology and novel approaches to case-finding, diagnosis, and treatment are causes for optimism but they need to be used cost-effectively. This in turn requires improved understanding of the epidemiology of TB and analysis of the effectiveness and cost-effectiveness of different interventions. We describe the contribution that mathematical modeling can make to understanding epidemiology and control of TB in different groups, guiding improved approaches to public health interventions. We emphasize that modeling is not a substitute for collecting data but rather is complementary to empirical research, helping determine what are the key questions to address to maximize the public-health impact of research, helping to plan studies, and making maximal use of available data, particularly from surveillance, and observational studies. We provide examples of how modeling and related empirical research inform policy and discuss how a combination of these approaches can be used to address current questions of key importance, including use of whole-genome sequencing, screening and treatment for latent infection, and combating drug resistance.

The impact of migration on tuberculosis epidemiology and control in high-income countries: a review

Tuberculosis (TB) causes significant morbidity and mortality in high-income countries with foreign-born individuals bearing a disproportionate burden of the overall TB case burden in these countries. In this review of tuberculosis and migration we discuss the impact of migration on the epidemiology of TB in low burden countries, describe the various screening strategies to address this issue, review the yield and cost-effectiveness of these programs and describe the gaps in knowledge as well as possible future solutions.The reasons for the TB burden in the migrant population are likely to be the reactivation of remotely-acquired latent tuberculosis infection (LTBI) following migration from low/intermediate-income high TB burden settings to high-income, low TB burden countries.TB control in high-income countries has historically focused on the early identification and treatment of active TB with accompanying contact-tracing. In the face of the TB case-load in migrant populations, however, there is ongoing discussion about how best to identify TB in migrant populations. In general, countries have generally focused on two methods: identification of active TB (either at/post-arrival or increasingly pre-arrival in countries of origin) and secondly, conditionally supported by WHO guidance, through identifying LTBI in migrants from high TB burden countries. Although health-economic analyses have shown that TB control in high income settings would benefit from providing targeted LTBI screening and treatment to certain migrants from high TB burden countries, implementation issues and barriers such as sub-optimal treatment completion will need to be addressed to ensure program efficacy.

Prevalence of and risk factors for active tuberculosis in migrants screened before entry to the UK: a population-based cross-sectional study

BACKGROUND

An increasing number of countries with low incidence of tuberculosis have pre-entry screening programmes for migrants. We present the first estimates of the prevalence of and risk factors for tuberculosis in migrants from 15 high-incidence countries screened before entry to the UK.

METHODS

We did a population-based cross-sectional study of applicants for long-term visas who were screened for tuberculosis before entry to the UK in a pilot programme between Oct 1, 2005, and Dec 31, 2013. The primary outcome was prevalence of bacteriologically confirmed tuberculosis. We used Poisson regression to estimate crude prevalence and created a multivariable logistic regression model to identify risk factors for the primary outcome.

FINDINGS

476 455 visa applicants were screened, and the crude prevalence of bacteriologically confirmed tuberculosis was 92 (95% CI 84-101) per 100 000 individuals. After adjustment for age and sex, factors that were strongly associated with an increased risk of bacteriologically confirmed disease at pre-entry screening were self-report of close or household contact with an individual with tuberculosis (odds ratio 11·6, 95% CI 7·0-19·3; p<0·0001) and being an applicant for settlement and dependant visas (1·3, 1·0-1·6; p=0·0203).

INTERPRETATION

Migrants reporting contact with an individual with tuberculosis had the highest risk of tuberculosis at pre-entry screening. To tackle this disease burden in migrants, a comprehensive and collaborative approach is needed between countries with pre-entry screening programmes, health services in the countries of origin and migration, national tuberculosis control programmes, and international public health bodies.

FUNDING

Wellcome Trust, Medical Research Council, and UK National Institute for Health Research.

Building Partnership to Improve Migrants' Access to Healthcare in Mumbai

Objectives

An intervention to improve migrants’ access to healthcare was piloted in Mumbai with purpose of informing health policy and planning. This paper aims to describe the process of building partnership for improving migrants’ access to healthcare of the pilot intervention, including the role played by different stakeholders and the contextual factors affecting the intervention.

Methods

The process evaluation was based on Baranowski and Stables’ framework. Observations in community and conversations with stakeholders as recorded in daily diaries, minutes of pre-intervention workshops, and stakeholder meetings served as data sources. Data were coded using the framework and descriptive summaries of evaluation components were prepared.

Results

Recruitment of stakeholders was easier than sustaining their interest. Community representatives led the intervention assisted by government officials. They planned community-level interventions to improve access to healthcare that involved predominantly information, education, and communication activities for which pre-existing formal and informal social networks and community events were used. Although the intervention reached migrants living with families, single male migrants neither participated nor did the intervention reach them consistently. Contextual factors such as culture differences between migrants and native population and illegality in the nature of the settlement, resulting in the exclusion from services, were the barriers.

Conclusion

Inclusive multi-stakeholder partnership, including migrants themselves and using both formal and informal networks in community is a feasible strategy for health education and has potential to improve the migrants’ access to healthcare. However, there are challenges to the partnership process and new strategies to overcome these challenges need to be tested such as peer-led models for involvement of single male migrants. For sustaining such efforts and mainstreaming migrants, addressing contextual factors and having formal mechanisms for their inclusion are equally important.